Noise suppressor for hydraulic systems



lal zass FIPi-EOOZ SR OR 390339306 May 8, 1962 A. M. HALLENE ETAL 3,033,306

NOISE SUPPRESSOR FOR HYDRAULIC SYSTEMS Filed July 24, 1959 United States This invention relates to a noise suppressor for bydraulic systems, and is particularly applicable to hydraulic elevator operating systems.

Modern hydraulic elevators operate at relatively high speeds, and accordingly the flow of liquid from one part of the system to another is noiser than was the case with the old lower Speed hydraulic systems. Applicants have discovered that a considerable amount of the objectionable noise in high speed hydraulic elevator systems results from the flow of liquid out of the high pressure side of the system, through the down travel and down leveling valves, and into the low pressure side of the system. This invention is directed to a suppressor which substantially eliminates, or greatly reduces, the noise resulting from this liquid flow.

In accordance with the present invention, the entrance to the low pressure side of the system, from the down travel and down leveling valves, is provided with a suppressor which operates by dividing the flow of liquid into laminar lines having but little turbulence, while producing but little detectable change in the hydraulic characteristics of the liquid flowing through the low pressure side of the system.

Thus, the principal object of the present invention is to provide a noise suppressor for a hydraulic system which has a high pressure line, a low pressure line, and a valve for selectively releasing liquid from the high pressure line to the low pressure line.

Another object of the invention is to provide a noise suppressor which has no substantial effect upon the hy draulic characteristics of the liquid in the low pressure line.

Yet another object of the invention is to provide a noise suppressor for hydraulic systems which is of simple construction and may be fabricated from commercially available components.

The invention is illustrated in a preferred embodiment in the accompanying drawings in Which:

FIG. 1 is a diagrammatic view, partly in section, of a hydraulic elevator system in which the suppressor of the present invention is used;

FIG. 2 is a longitudinal central sectional view on a scale larger than FIG. 1 of a noise suppressor of the character employed in the system of FIG. 1, taken substantially as illustrated along the line 22 of FIG. 3; and

FIG. 3 is an end elevational view of the noise suppressor.

Referring to the drawings in greater detail, and re ferring first to FIG. 1, the elevator system includes a liquid reservoir 10, a hydraulic cylinder 11, an elevator plunger 12 slidably mounted in the cylinder and surmounted by an elevator car 13, together with suitable piping, valves and pump mechanism for moving hydraulic fluid between reservoir and cylinder 11.

A main oil supply line 14 connects reservoir 10 with a positive displacement pump 15 which pumps hydraulic fluid into a manifold 16, through a shockless check valve 17, and through a further manifold 18 into cylinder 11. Pump 15 is provided with a pulley 15a by means of which the pump may be driven by a belt 15b connected to a suitable electric motor (not shown).

Assume the elevator to be standing at a flood landing, operation of the control for up travel of the elevator starts the pump, and initial flow of liquid is through manifold 16, a pressure controlled, normally open starting valve 19, a return manifold 20 and return line 21 to the reservoir 10. As pressure develops in valve 19, its hydraulic control head 19a gradually causes the valve to close, and liquid is forced through check valve 17, manifold 18 and into cylinder 11.

When the elevator car reaches another floor landing at which it is to stop, suitable controls at the floor landing and on the elevator car actuate a solenoid 22a of a solenoid up leveling valve 22 which opens to bypass part of the liquid from pump 15 through a flow regulator system, indicated generally at 23, and back to reservoir 10 through return line 21. Operation of the up leveling system, and in particular the system including fiow regulator means 23, is described in detail and claimed in copending application of Walter Beck, Serial No. 618,800, filed October 29, 1956, now Patent 2,944,- 401, issued July 12, 1960.

Downward travel of elevator 13 is controlled by a main down travel valve 24 having a solenoid 24a, and a down leveling valve 25 having a solenoid 25a. Down valve 24 controls flow of liquid from a high pressure line 26 connected to manifold 18, to a low pressure line 27 connected with low pressure return manifold 20. Similarly, down leveling valve 25 controls flow of liquid from a high pressure line 28 into a low pressure line 29. Entrance of liquid from valve 24 into low pressure line 27 is through a noise suppressor 30, while entrance of liquid from valve 25 into low pressure line 29 is through a noise suppressor 31.

FIGS. 2 and 3 illustrate suppressor 30; and suppressor 31 is identical with 30 except for a dilference in diameter. Accordingly, only the suppressor 30 will be described in detail.

A short pipe nipple 32 provides a suppressor casing which is threaded at 33 for connection to the housing of valve 24, and secured within casing 32 is an outer group of tubes 33 and an inner group of tubes 34. As seen in FIG. 3, tubes 33 of the outer group are solder bonded to the inner face of casing 32, and to each other, as indicated at 33a and 33b in FIG. 3; and tubes 34 of the inner group are solder bonded to the tubes of the outer group at 34a and to each other at 34b. Low pressure lines 27 and 29 consist of sections of hose which are clamped to the respective suppressors 30 and 31 by clamps 27a and 29a, and which are clamped to stubs on low pressure manifold 20 by clamps 27b and 29b.

As a specific example of a noise suppressor 30 which has proved satisfactory, casing 32 is a 1% inch inside diameter seamless pipe nipple, while tubes 33 of the outer group are "7 inch outside diameter seamless steel tubing of 24 gauge, while tubes 34 of the inner group are inch outside diameter seamless steel tubing of 24 gauge. It is essential that flow dividing tubes 33 and 34 be thin walled and of relatively large diameter, so that they do not produce an excessive reduction in the cross sectional area of casing 32 which is available for liquid flow. The tolerable percentage of reduction in flow area available for liquid depends-upon the diameter of the low pressure outlet of the valve and the conditions on the low pressure side of the system. It is obvious that if a valve has a very large outlet which can much more than take care of the return flow to manifold 20, a relatively larger reduction in flow area may be tolerated without adverse effect upon the hydraulic characteristics of the system. However, for a valve adapted to receive a nipple of 1 inch inside diameter, the maximum tolerable area of reduction within suppressor casing 32 is 20%.

Since the starting valve 19 and up leveling valve 22 are open only for brief periods of time, noise suppression at the low pressure side of those valves is less important than on the down travel and down leveling valves, at least one of which is always open during down travel of the elevator car. Nevertheless, noise suppressors are of some benefit on valves 19 and 22 and accordingly, a suppressor 30 is shown in the drawings on the low pressure side of each of those valves.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom for some modification will be obvious to those skilled in the art.

We claim:

1. In a hydraulic system, a valve connected to a high pressure line, a low pressure line, a noise suppressor comprising a casing interconnecting said valve and said low pressure line, said casing having therein axially extending, tubular flow directing means extending substantially the entire length of said casing.

2. In a hydraulic system, a valve connected to a high pressurel line, a low pressure line, a noise suppressor comprising a casing interconnecting said valve and said low pressure line, said casing having therein flow directing means defining a plurality of substantially unidirectional coextensive passages extending from said valve toward said low pressure line.

3. The system of claim 2 in which the suppressor casing is a pipe nipple secured to the valve.

4. The system of claim 2 in which the flow directing means comprises a plurality of open ended, thin walled tubes secured in the casing with their axes parallel to the axis of the casing.

5. The device of claim 4 in which said tubes define an outer group bonded to the casing wall and to one another, and an inner group bonded to the tubes of the outer group and to each other.

References Cited in the file of this patent UNITED STATES PATENTS 

